Fluoroolefins represented by the formula: CF3(CX2)nCF═CH2, the formula: CF3(CX2)nCH═CHF (wherein X represents H or F, and n is an integer of 0 or more), and the like are useful compounds as various functional materials, solvents, refrigerants, blowing agents, and monomers for functional polymers or starting materials of such monomers. For example, fluoroolefins are used as monomers for modifying ethylene-tetrafluoroethylene copolymers. In particular, of the fluoroolefins mentioned above, 2,3,3,3-tetrafluoropropene (HFO-1234yf) represented by CF3CF═CH2 has recently gained attention because it offers promising prospects as a refrigerant compound of low global-warming potential.
A known method for producing HFO-1234yf is a method in which halopropane or halopropane used as a starting material is fluorinated with hydrogen fluoride (HF). For example, when 1,1,1,2,3-pentachloropropane (HCC-240db) used as a starting material is fluorinated in a gas phase, the reactions proceed in the route as described below (Patent Document 1).CCl3CHClCH2Cl+3HF→CF3CCl═CH2+4HCl  (1)CF3CCl═CH2+HF→CF3CFClCH3  (2)CF3CFClCH3→CF3CF═CH2+HCl  (3)Alternatively, the reactions may proceed in the route as described below without the reaction step of chemical reaction formula (2).CCl3CHClCH2Cl+3HF→CF3CCl═CH2+4HCl  (1)CF3CCl═CH2+HF→CF3CF═CH2+HCl  (4)(Patent Document 2)
Further, as another method for producing HFO-1234yf, it is also possible to produce HFO-1234yf in a manner similar to the method represented by chemical reaction formulas (1) to (3) using 1,1,2,3-tetrachloropropene (HCO-1230xa) as a starting material instead of HCC-240db (Patent Document 3).
In all of the above methods that have previously been suggested, 2, 3, or more reaction steps are required to produce the desired HFO-1234yf from the starting material, i.e., halopropane or halopropene. In contrast, Patent Documents 4 and 5 found a method of producing HFO-1234yf by fluorinating the starting material, i.e., halopropane or halopropene, in a single reactor, although the yield is small. Patent Documents 4 and 5 also suggest a process for recycling 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf), which is the major product of the reaction and may be used as an intermediate of HFO-1234yf. However, when the recycling process is actually performed with the conditions specified in the Examples of these prior art documents, unreacted HCFO-1233xf, HF, and the like successively increase in the system, making it impossible to constantly carry out the step. Therefore, to solve this problem, a step of removing unreacted HCFO-1233xf, HF, and the like to the outside of the system, a storing device, a separate reaction treatment, and the like will be necessary, thereby increasing facility cost and production cost.